Blood pressure monitor

ABSTRACT

Described herein are methods, systems, and software for monitoring blood pressure. In some embodiments, a using a mobile device is used. The blood pressure monitoring system utilizes heart rate measurements at two separate locations on the body to calculate a differential pulse arrival time which is used to estimate blood pressure. The heart rate measurements can be taken simultaneously, or they can be taken sequentially while simultaneously taking ECG measurement. If taken sequentially, the heart rate measurements are aligned with the ECG to determine the differential. Accurate, inexpensive, and discreet blood pressure monitoring is thus provided.

CROSS-REFERENCE

This application claims the benefit of U.S. Provisional Application No.61/989,279, filed May 6, 2014, which application is incorporated hereinby reference.

INCORPORATED BY REFERENCE STATEMENT

All publications, patents, and patent applications mentioned in thisspecification are herein incorporated by reference to the same extent asif each individual publication, patent, or patent application wasspecifically and individually indicated to be incorporated by reference.

U.S. Ser. No. 13/420,520, filed Mar. 14, 2012, now U.S. Pat. No.8,301,232, is hereby expressly incorporated herein by reference in itsentirety.

BACKGROUND

Blood pressure is a key vital sign monitored by physicians, it is usedfor the diagnosis of many medical conditions, and by itself is monitoredas a key metric for the management of disease. The standard measure ofblood pressure is the auscultatory method, wherein a specialist inflatesa cuff around the arm and uses a stethoscope to determine the systolicblood pressure and the diastolic blood pressure. Hypertension, anelevation in either the systolic or diastolic blood pressure, is amedical condition that afflicts some 70 million Americans, and it isestimated that only about half of these people have their disease undercontrol.

SUMMARY

The presently claimed and disclosed concepts relate generally to heartmonitoring devices and methods and, more particularly, but not by way oflimitation, to methods, devices, systems and software for measuringblood pressure using a mobile device. The methods described in thisdisclosure are in stark contrast to standard blood pressure methods. Themethod requires the use of a cuff, which is bulky, costly, and does notallow continuous monitoring. There is an unmet need for blood pressuremonitoring, especially in personal healthcare applications. Compared tostandard methods of blood pressure monitoring, the methods of thedisclosure provide advantages with regard to cost, convenience, and theability to intermittently or continuously monitor blood pressure for themanagement of disease or for research purposes.

Disclosed herein, is a method for non-invasive determination of a bloodpressure in a subject, said method comprising; providing to a subject amobile computing device comprising a first and a second electrode and anoptical sensor, wherein said first and second electrodes are configuredto sense an electrocardiogram (ECG), wherein said optical sensor isconfigured to sense a photoplethysmogram (PPG), wherein a softwareapplication is configured to determine a differential pulse arrival timeusing input from said first and second electrodes and said opticalsensor, and display a blood pressure reading of said subject based onthe differential pulse arrival time. In certain embodiments, said mobilecomputing device comprises a smartphone. In certain embodiments, saidmobile computing device comprises a tablet. In certain embodiments, saidmobile computing device comprises a smart watch. In certain embodiments,said optical sensor is a camera that operates at a minimum of 30 framesper second. In certain embodiments, said first and second electrodes areremovable from said mobile computing device.

Disclosed herein is a method for non-invasive determination of a bloodpressure in a subject, said method comprising; providing to the subjecta software application configured for use with a mobile computingdevice, wherein said mobile computing device comprises a first and asecond electrode and an optical sensor, wherein said first and saidsecond electrodes are configured to sense an electrocardiogram, whereinsaid optical sensor is configured to sense a photoplethysmogram, whereinsaid software application is configured to determine a differentialpulse arrival time using input from said first and second electrodes andsaid optical sensor, and display a blood pressure reading of saidsubject based on the differential pulse arrival time. In certainembodiments, said mobile computing device comprises a smartphone. Incertain embodiments, said mobile computing device comprises a tablet. Incertain embodiments, said mobile computing device comprises asmartwatch. In certain embodiments, said optical sensor is a camera thatoperates at a minimum of 30 frames per second. In certain embodiments,said first and second electrodes are removable from said mobilecomputing device.

Also disclosed herein, is method for non-invasive determination of ablood pressure in a subject, said method comprising; engaging, by saidsubject, a first electrode on a mobile computing device with a firstskin surface, and a second electrode on said mobile computing devicewith a second skin surface such that a first and a secondelectrocardiogram is sensed; engaging, by said subject, simultaneouslyto engaging said first and said second electrodes, an optical sensor onsaid mobile computing device such that a first and a secondphotoplethysmogram is sensed from different body locations; and whereinsaid mobile computing device includes software configured to generate anaverage electrocardiogram from said first and said secondelectrocardiograms, wherein said software is configured to determine adifferential pulse arrival time based on said average electrocardiogramand said first and said second photoplethysmograms, and wherein saidsoftware is configured to determine said blood pressure of said subjectbased on said differential pulse arrivalion time. In an embodiment, saidsoftware application is configured to communicate with a network server.In certain embodiments, said mobile computing device comprises asmartphone. In certain embodiments, said mobile computing devicecomprises a tablet. In certain embodiments, said mobile computing devicecomprises a smartwatch.

Also disclosed herein, is a system for non-invasive determination of ablood pressure in a subject, comprising; a mobile computing devicecomprising a processor, an optical sensor, and a display; a first and asecond electrode attached to said mobile computing device, coupled tosaid processor; and a non-transitory computer readable storage mediumencoded with a computer program including instructions executable bysaid processor to cause said processor to; receive a firstelectrocardiogram from said first and second electrodes and receive atthe same time a first photoplethysmogram from said optical sensor;receive a second electrocardiogram from said first and second electrodesand receive at the second time a second photoplethysmogram from saidoptical sensor; generate an average electrocardiogram from said firstand second electrocardiograms; determine a differential pulse arrivaltime based on said average electrocardiogram and said first and secondphotoplethysmograms; and determine said blood pressure of said subjectbased on said differential pulse arrival time. In certain embodiments,said software application is configured to communicate with a networkserver. In certain embodiments, said mobile computing device comprises asmartphone. In certain embodiments, said mobile computing devicecomprises a tablet. In certain embodiments, said mobile computing devicecomprises a smart watch. In certain embodiments, said optical sensor isa camera that operates at a minimum of 30 frames per second. In certainembodiments, said optical sensor is a camera that operates at a minimumof 60 frames per second. In certain embodiments, said first and secondelectrodes are removable from said mobile computing device. In certainembodiments, the system further comprises a dedicated means to initiatethe steps of the system.

Also described herein is a method for the non-invasive determination ofblood pressure in a subject, the method comprising using a first opticalsensor to detect a pulse in the subject at a first location of thesubjects body using a second optical sensor to detect a pulse in thesubject at a second location of the subjects body at the same time; andcalculating the blood pressure of the subject using a non-transitorycomputer readable storage media with a computer program configured tocalculate a differential pulse arrival time between the first locationand the second location; wherein the method does not utilize a bloodpressure cuff or acoustic device to sense a subjects pulse. In anembodiment, the first location is a finger of the subject. In anembodiment, the second location is the subjects face. In an embodiment,the method utilizes a mobile phone. In an embodiment, the methodutilizes a tablet computer. In an embodiment, the method utilizes asmart watch. In an embodiment, at least one of the optical sensors is acamera. In an embodiment, the camera has a speed of 30 frames per secondor greater. In an embodiment, the camera has a speed of 60 frames persecond or greater. In an embodiment, the output of the computer programis sent to a network server.

Also described herein is a method for the non-invasive determination ofblood pressure in a subject, the method comprising: using electrodes todetect the ECG of a subject; (a) using an optical sensor or camera todetect a pulse in the subject at a first location of the subjects body;(b) repeating steps (a) and (b) at a second location of the subjectsbody; and (c) calculating the blood pressure of the subject using anon-transitory computer readable storage media with a computer programconfigured to calculate a pulse arrival time; wherein the method doesnot utilize a blood pressure cuff or acoustic device to sense a subjectspulse. In an embodiment, the electrodes detect a QRS complex at thehands of the subject. In an embodiment, at either the first or secondlocation that optical sensor detects is the subjects face. In anembodiment, the method utilizes a mobile phone. In an embodiment, themethod utilizes a tablet computer. In an embodiment, the method utilizesa smart watch. In an embodiment, the optical sensors is a camera orcameras. In an embodiment, the camera or cameras have a speed of 30frames per second or greater. In an embodiment, the camera or camerashave a speed of 60 frames per second or greater. In an embodiment, theoutput of the computer program is sent to a network server.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the described subject matter are set forth withparticularity in the appended claims. A better understanding of thefeatures and advantages of the presently described subject matter willbe obtained by reference to the following detailed description that setsforth illustrative embodiments, in which the principles of the describedsubject matter are utilized, and the accompanying drawings of which:

FIG. 1 shows a simplified schema for time alignment of PPG measurements.

FIG. 2 shows a non-limiting example of a person using a mobile device todetermine their blood pressure.

FIG. 3 shows a non-limiting example of a finger placed over a rearfacing camera of a mobile phone for a photoplethysmogram (PPG)measurement.

FIG. 4 shows hand placement on a device equipped with electrodes formeasuring a QRS complex.

FIG. 5 shows a front view of a device which can implement the methods ofthis disclosure.

FIG. 6 shows a side view of a device which can implement the methods ofthis disclosure.

FIG. 7 shows a rear view of a device which can implement the methods ofthis disclosure.

FIG. 8 shows a rear view of a device with electrodes attached which canimplement the methods of this disclosure.

DETAILED DESCRIPTION

Before explaining at least one embodiment of the inventive conceptsdisclosed herein in detail, it is to be understood that the inventiveconcepts are not limited in their application to the details ofconstruction, experiments, exemplary data, and/or the arrangement of thecomponents set forth in the following description, or illustrated in thedrawings. The presently disclosed and claimed inventive concepts arecapable of other embodiments or of being practiced or carried out invarious ways. Also, it is to be understood that the phraseology andterminology employed herein is for purpose of description only andshould not be regarded as limiting in any way.

In the following detailed description of embodiments of the inventiveconcepts, numerous specific details are set forth in order to provide amore thorough understanding of the inventive concepts. However, it willbe apparent to one of ordinary skill in the art that the inventiveconcepts within the disclosure may be practiced without these specificdetails. In other instances, well-known features have not been describedin detail to avoid unnecessarily complicating the instant disclosure.

Certain Definitions

Further, unless expressly stated to the contrary, “or” refers to aninclusive or and not to an exclusive or. For example, a condition A or Bis satisfied by any one of the following: A is true (or present) and Bis false (or not present), A is false (or not present) and B is true (orpresent), and both A and B are true (or present).

In addition, use of the “a” or “an” are employed to describe elementsand components of the embodiments herein. This is done merely forconvenience and to give a general sense of the inventive concepts. Thisdescription should be read to include one or at least one and thesingular also includes the plural unless it is obvious that it is meantotherwise.

Finally, as used herein, any reference to “one embodiment” or “anembodiment” means that a particular element, feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment. The appearances of the phrase “in oneembodiment” in various places in the specification are not necessarilyall referring to the same embodiment.

While the term “extremities” is used herein for the body area used todetect heart rate, it need not be an extremity and could be, forexample, a chest or stomach location on the body. In general, using aposition close to the heart and comparing to a position far from theheart will provide the longest differential and therefore increasedaccuracy.

A “subject” as defined by this disclosure can be any human person inwhich blood pressure monitoring would be advantageous. The person canhave a diagnosed illness, including but not limited to, primaryhypertension, secondary hypertension, or gestational hypertension. Theperson can be considered healthy and undiagnosed with any disease. Themethods of this disclosure include monitoring of both healthy personsand those diagnosed with a medical condition.

Non-Invasive Blood Pressure Measurements

Pressure waves produced at the heart propagate through the arteries at acertain velocity known as the pulse wave velocity (PWV). The PWV dependson the blood pressure and the elastic properties of arteries. A person'sblood pressure has been shown to be proportional to, or a function of,the pressure wave velocity. The PWV is equal to the length of a vessel(l) divided by the time it takes for a pressure pulse to arrival througha vessel. The time it takes for a pressure pulse to travel the length ofthe vessel (l) is known as the pulse transit time (PTT) or pulse arrivaltime (PAT). PTT and PAT are used interchangeably herein. The formula fordetermination of the PWV is as follows:PWV=l/PTTThe PAT is considered to have a correlation with blood pressure, andattempts have been made to use the PAT for indirect blood pressuremeasurements.

It was once thought that the PAT could be estimated as the time betweenthe QRS peak on an ECG and the time the wave or pulse of blood reachesan extremity. The QRS peak could be measured using known ECG devices,and the time the pulse of blood reaches an extremity could be measuredusing known methods such as photoplethysmogram (PPG). The PPG methoddetects changes in blood volume during a cardiac cycle by illuminatingthe skin, and measuring changes in light absorption. PPG has become apopular method for measuring heart rate and oxygen saturation by using,for example, a mobile phone's embedded flash as a light source and thecamera as a light sensor when held adjacent a peripheral site such asthe finger. The PPG measurement can also be made at another peripheralsite such as the ear, forehead, or chest. The PPG signal obtainedconsists of pulses that reflect the change in vascular blood volume witheach cardiac beat.

Such time measurements used for the PWV included a “pre-ejection”period, which is the time interval from the beginning of electricalstimulation of the ventricles to the actual opening of the aortic valve.The aortic valve will not open until the blood pressure within theventricle is greater than the pressure in the aorta. Thus, presentattempts to measure PWV actually use a length of artery divided by thesum of the pre-ejection period plus the time for the pulse to travelthat length of artery.

By making simultaneous PPG measurements at different locations of thebody, the effect of the pre-ejection period can be eliminated bysubtraction. PPG measurements can be made by a mobile device equippedwith a camera. Key to eliminating the effect of the pre-ejection periodis calculating a differential PAT, i.e. the difference between when thepulse reaches extremity A and when it reaches extremity B. Thiseliminates the pre ejection period, because it is the same for bothextremities, and is removed by using the differential PAT(PAT_(A)−PAT_(B)). The differential PAT time can be measured, forexample, by using a mobile phone having both front and back cameras, andthus perform PPG measurements simultaneously at two different locationsof the body. By using the differential PAT one can calculate a PWV usingthe following equation:PWV=(l _(A) −l _(B))/(PTT _(A) −PTT _(B))If repeated measurements are made at the same body locations over time,then the length (l) of the pulse arrival need not be determined. Sinceblood pressure is proportional to the PWV, and the PWV is inverselyproportional to the differential PAT, blood pressure can be determinedby calculating the differential PAT. If the PAT can be correlated toblood pressure by an independent method, for example, the auscultatorymethod or an automated oscillometric blood pressure device at home onecan track changes in blood pressure, merely by tracking changes in PAT.

Alternatively a differential PAT can be calculated using two successive,not simultaneous, PPG measurements, if an ECG is also employed tosynchronize the PPG measurements. If successive ECG measurements andtheir corresponding PPG measurements are made, they can be time alignedby averaging the QRS readings from the ECGs associated with each PPGmeasurement, and then aligning the PPG measurements taken to the averageQRS. This will result in two PATs derived from average QRS complexes.The differential PAT is the difference between these two PATs. Aschematic of this process is shown in FIG. 1. In this way the effect ofthe pre-ejection period can be minimized. As with the previous methodthe differential PAT can be correlated to blood pressure by anindependent method, for example, the auscultatory method or an automatedoscillometric blood pressure device at home allowing one to trackchanges in blood pressure, merely by tracking changes in thedifferential PAT.

By occasionally calibrating an individual's PAT to a given bloodpressure as measured by, for example, the auscultatory method or anautomated oscillometric device at home, one can calibrate thedifferential PAT with blood pressure. As a result one can utilize amobile device throughout the day to track their blood pressure whenother methods may not be convenient. In certain embodiments, the methoddescribed herein requires calibration once a day. In certainembodiments, the method described herein requires calibration everyother day. In certain embodiments, the method described herein requirescalibration 2, 3, 4, or 5 times a week. In certain embodiments, themethod described herein requires calibration once a week. In certainembodiments, the calibration is adaptive, whereby multiple calibrationevents are stored and used to improve the overall accuracy of themethod.

Certain Embodiments of the Disclosure

Disclosed herein is a method for non-invasive determination of a bloodpressure in a subject, said method comprising: providing to a subject amobile computing device comprising a first and a second electrode and anoptical sensor, wherein said first and second electrodes are configuredto sense an electrocardiogram, wherein said optical sensor is configuredto sense a photoplethysmogram, wherein a software application isconfigured to determine a differential pulse arrival time using inputfrom said first and second electrodes and said optical sensor, anddisplay a blood pressure reading of said subject based on thedifferential pulse arrival time.

Non limiting embodiments of exemplar mobile computing devices that canexecute the methods of this disclosure are shown in FIGS. 2-5. Incertain embodiments, the mobile computing device is a mobile phone. Incertain embodiments, the mobile computing device is a smart phone. Incertain embodiments, the mobile computing device is a tablet computer.In certain embodiments, the mobile computing device is a smart watch. Incertain embodiments, the mobile computing device is a portable laptopcomputer. In certain embodiments, the mobile computing device is adedicated device for measuring vital signs. In certain embodiments, themobile computing device is a dedicated device for measuring bloodpressure.

In certain embodiments, the mobile computing device communicates with anetwork server. In certain embodiments, the mobile computing devicecommunicates with a network server by Wi-Fi. In certain embodiments, themobile computing device communicates with a network server using acellular network. In certain embodiments, the mobile computing devicecommunicates with another computer wirelessly. In certain embodiments,the mobile computing device communicates with another computer byBluetooth™. In certain embodiments, the mobile computing devicecommunicates with another computer by a wired connection.

In certain embodiments, the mobile device has a single optical sensor.In certain embodiments, the mobile computing device has two opticalsensors. In certain embodiments, the mobile computing device has threeoptical sensors. In certain embodiments any or all of the opticalsensors is a camera. In certain embodiments, any or all of the camerasoperate with a speed of equal to or greater than 30 frames per second.In certain embodiments, any or all of the cameras operate with a speedof equal to or greater than 60 frames per second. In certainembodiments, any or all of the cameras operate with a speed of equal toor greater than 120 frames per second. In certain embodiments eachoptical sensor is paired with a means of illumination. The means ofillumination could be an LED.

In certain embodiments, the mobile computing device has an opticalsensor that is a forward-facing camera 1, which can be positionedanywhere on the device that allows an unobstructed view of the subjector a location on the subjects body while being held. In certainembodiments the camera can be configured to operate as a PPG. In certainembodiments, the camera speed is equal to or greater than 30 frames persecond. In certain embodiments, the camera speed is equal to or greaterthan 60 frames per second. In certain embodiments, the camera speed isequal to or greater than 120 frames per second. In certain embodiments,the camera uses a charge couple device (CCD) sensor. In certainembodiments, the camera uses complementary metal oxide semiconductor(CMOS) sensor. In certain embodiments the camera has a resolution of 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20megapixels or more. In certain embodiments, the device also contains asource of illumination 2 which can be used to aid the camera indetecting and imaging a location of the subjects body, and in PPGmeasurements. In certain embodiments, the source of illumination is anLED. In certain embodiments, the LED can be illuminated continuously orintermittently.

In certain embodiments, the mobile computing device has an opticalsensor that is a rear-facing camera 4, which can be positioned anywhereon the device that allows an unobstructed view of the subject or alocation on the subjects body while being held. In certain embodimentsthe camera can be configured to operate as a PPG. In certainembodiments, the camera speed is equal to or greater than 30 frames persecond. In certain embodiments, the camera speed is equal to or greaterthan 60 frames per second. In certain embodiments, the camera speed isequal to or greater than 120 frames per second. In certain embodiments,the camera uses a charge couple device (CCD) sensor. In certainembodiments, the camera uses complementary metal oxide semiconductor(CMOS) sensor. In certain embodiments the camera has a resolution of 1,2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20megapixels or more. In certain embodiments, the device also contains asource of illumination 5 which can be used to aid the camera indetecting and imaging a location of the subjects body, and in PPGmeasurements. In certain embodiments, the source of illumination is anLED. In certain embodiments, the LED can be illuminated continuously orintermittently.

In certain embodiments, the mobile computing device has a display 3which can be utilized as a graphical user interface. In certainembodiments, the display can be touch sensitive. The device can receiveinstructions and parameters from the user via the display 3. The displaycan communicate instructions to the user, aid in positioning of at leastone camera, and display results of the monitoring. In some embodiments,the device may be controlled by voice commands. In some embodiments thedevice may be controlled remotely.

A non-limiting embodiment of a mobile computing device that can beconfigured to measure a subjects blood pressure using ECG measurementsis shown in FIG. 5. The device can have dual electrodes 6 to measure anelectrical potential difference used to calculate a heartbeat. Incertain embodiments, the electrodes are integrated into the device. Incertain embodiments, the electrodes are separate from the device in theform of a removable cover. In certain embodiments the electrodes are onthe back of the device. In certain embodiments, the electrodes are onthe sides of the device. In certain embodiments, the electrodes are onthe front of the device. In certain embodiments, the electrodes areergonomically shaped.

In certain embodiments, the mobile computing device may have a meansdedicated to initiating the method of measuring blood pressure describedherein. In certain embodiments, the means may be a button, switch,toggle switch, capacitive interface, voice command, remote command orthe like. In certain embodiments, the mobile computing device mayprovide auditory feed-back. In certain embodiments, the auditoryfeedback may guide the user for proper use of the device, alert the useras to when the device is being used incorrectly, alert the user as towhen measurements are being made, alert the user as to the outcome ofmeasurements, alert the user for a need to calibrate or otherwiseservice the device.

In certain embodiments, any part of the body can utilized to make PPGmeasurements. In certain embodiments, a finger can utilized to make PPGmeasurements. In certain embodiments, the face can utilized to make PPGmeasurements. In certain embodiments, an ear can utilized to make PPGmeasurements. In certain embodiments, the chest can utilized to make PPGmeasurements. In certain embodiments, the stomach can utilized to makePPG measurements. In certain embodiments, the neck can utilized to makePPG measurements.

Also disclosed herein is a method for non-invasive determination of ablood pressure in a subject, said method comprising: providing to thesubject a software application configured for use with a mobilecomputing device, wherein said mobile computing device comprises a firstand a second electrode and an optical sensor, wherein said first andsaid second electrodes are configured to sense an electrocardiogram,wherein said optical sensor is configured to sense a photoplethysmogram,wherein said software application is configured to determine adifferential pulse arrival time using input from said first and secondelectrodes and said optical sensor, and display a blood pressure readingof said subject based on the differential pulse arrival time.

In certain embodiments, the software application controls the opticalsensor. In certain embodiments, the software application controls thefirst and second electrodes. In certain embodiments, the softwareapplication calculates a differential PAT. In certain embodiments, thesoftware application correlates a differential PAT with a blood pressureusing calibration data. In certain embodiments, the software applicationcalculates an average QRS from two or more ECG readings. In certainembodiments, the software application calculates an average QRS from 3,4, 5, 6, 7, 8, 9, 10 or more ECG readings. In certain embodiments, thesoftware application calculates an average QRS from 10, 20, 30, 40, 50,6, 70, 80, 90, 100 or more ECG readings. In certain embodiments, thesoftware application correlates a differential PAT with a blood pressureusing calibration data. In certain embodiments, the software applicationcorrelates a differential PAT with a blood pressure using calibrationdata. In certain embodiments, the software can be configured formultiple users. In certain embodiments the software stores individualdifferential PAT data points. In certain embodiments the software storesindividual differential PAT data points that are tagged with meta-datasuch as time of day, date, geolocation and user.

Software downloadable to a mobile computing device can correlate anindividual's blood pressure and differential PAT. An individual owningsuch a mobile computing device can, for example, measure their bloodpressure using a standard cuff-type blood pressure monitor in themorning and then measure their differential PAT to calibrate thecorrelation between blood pressure and differential PAT. The rest of theday, they can quickly and inconspicuously monitor their blood pressureby merely measuring the differential PAT with their mobile computingdevice. In certain embodiments, the software application describedherein requires calibration once a day. In certain embodiments, thesoftware application described herein requires calibration every otherday. In certain embodiments, the software application described hereinrequires calibration 2, 3, 4, or 5 times a week. In certain embodiments,the software application described herein requires calibration once aweek. In certain embodiments, the calibration is adaptive, wherebymultiple calibration events are stored and used to improve the overallaccuracy of the software.

The software application can allow for the input of biometric data suchas height, weight, arm length, leg length, waist circumference, gender,age birthdate and the like. The software uploaded to the mobile devicecan provide management tools to the user. The tools can include storingblood pressure readings calculating daily, weekly or monthly averages.The stored blood pressure readings can be used to generate a report foruse by the subject, a physician, or for a clinical or investigationaltrial. The report can be sent to health management and trackingsoftware, an e-mail address, a secure server or a social network. Thesoftware can be configured to send alerts via e-mail, text message, orsocial media. The software can also interface with a wearable fitnessdevice such as a Fitbit™, in order to correlate blood pressure withpulse rate, body temperature, sleep-wake cycles, circadian rhythms,movement or any other vital sign or biometric data of interest to theuser, a physician, or a clinical or investigational trial.

Disclosed herein is a system for non-invasive determination of a bloodpressure in a subject, comprising; a mobile computing device comprisinga processor, an optical sensor, and a display; a first and a secondelectrode attached to said mobile computing device, coupled to saidprocessor; and a non-arrivalory computer readable storage medium encodedwith a computer program including instructions executable by saidprocessor to cause said processor to: receive a first electrocardiogramfrom said first and second electrodes and receive at the same time afirst photoplethysmogram from said optical sensor; receive a secondelectrocardiogram from said first and second electrodes and receive atthe same time a second photoplethysmogram from said optical sensor;generate an average electrocardiogram from said first and secondelectrocardiograms; determine a differential pulse arrival time based onsaid average electrocardiogram and said first and secondphotoplethysmograms; and determine said blood pressure of said subjectbased on said differential pulse arrival time.

Herein are presented various non limiting practical examples of thesystems, methods and devices of this disclosure.

Example 1—Measurement of Blood Pressure in an Individual Using DualOptical Sensors

A non-limiting example of one embodiment of the method requires holdinga mobile phone in front of one's face as shown in FIG. 6, detecting thepulse on a finger covering the camera lens on the back of the mobilephone as shown in FIG. 7, and simultaneously detecting the pulse onone's face using the camera on the front of the mobile phone, the timelag between the finger pulse and the face pulse can be calculated as thedifferential PAT, and eliminates the pre-ejection period and errorscaused by inclusion of the pre-ejection period. The mobile phone can beheld at any distance from the face that allows for proper imaging. Incertain embodiments, the phone is held less than 3 feet from the face.In certain embodiments, the phone is held less than 2 feet from theface. In certain embodiments, the phone is held less than 1 foot fromthe face. In certain embodiments, the phone is held less than 6 inchesfrom the face. In certain embodiments, the phone can be used to detectthe pulse at a location of the body other than the face, this locationcan be the neck, chest, stomach or any other location suitable fordetecting a pulse. In certain embodiments the methods of this disclosurecan be carried out using a tablet computer. In certain embodiments themethods of this disclosure can be carried out using a smart watch. Incertain embodiments the methods of this disclosure can be carried outusing a device that is solely intended to monitor vital signs.

In a second non-limiting embodiment of this method, a subject can hold afirst finger over the forward facing camera, and a second finger overthe rear-facing camera of a mobile device. PPG measurements can then bemade, and the differential PAT calculated. Using the differential PATblood pressure can be calculated in a way similar to the firstembodiment.

Example 2—Measurement of Blood Pressure in an Individual Using a SingleOptical Sensor and an ECG

Some individuals may not have a mobile device with front and back cameraability or the frames per second or resolution of the available frontcamera may not be sufficient to provide accurate blood pressurecorrelations. However, by using a mobile device enabled to take ECGmeasurements, such as described in U.S. Pat. No. 8,301,232, it ispossible to use a mobile device to measure the pulse at one extremitywhile simultaneously taking ECG measurements, and then measure the pulseat another extremity or position while again simultaneously taking ECGmeasurements. The heart rate signals are then aligned with the ECGsignals to determine a time difference or differential PAT. Thedifferential PAT, once calibrated to the individual, can be used toestimate and track blood pressure.

For example, a person can place their left and right hands on theelectrodes of a mobile phone back cover or protective case configured tomeasure and record ECG measurements, as shown in FIG. 8, whilesimultaneously placing a finger over the back camera lens on the mobiledevice. Software then calculates a PAT from the initiation of the QRScomplex to the sensing of blood flow at the finger using the camera ofthe mobile device as a PPG. These steps can be repeated using adifferent location of the body such as a finger from the other hand orfoot. Software downloadable to the mobile device averages the two QRSsignals from the ECG, and time-aligns the two PPG measurements with theaveraged ECG to calculate the differential PAT. As described above,software downloadable to the mobile phone can correlate the differentialPAT to blood pressure. The correlation merely requires calibration afterusing a standard blood pressure measurement and consistent use of thesame extremities for measuring heart rate.

While preferred embodiments of the presently described subject matterhave been shown and described herein, it will be obvious to thoseskilled in the art that such embodiments are provided by way of exampleonly. Numerous variations, changes, and substitutions will now occur tothose skilled in the art without departing from the subject matterdescribed herein. It should be understood that various alternatives tothe embodiments of the subject matter described herein may be employedin practicing the subject matter described here. It is intended that thefollowing claims define the scope of the subject matter described hereinand that methods and structures within the scope of these claims andtheir equivalents be covered thereby.

What is claimed is:
 1. A method comprising: sensing, with a firstelectrode and a second electrode configured to operate with a mobilecomputing device, a first electrocardiogram (ECG) of a subject; sensing,with an optical sensor configured to operate with said mobile computingdevice, a first photoplethysmogram (PPG) of said subject simultaneouslyto sensing said first ECG of said subject; sensing with said firstelectrode and said second electrode, a second ECG of said subject;sensing with said optical sensor, a second PPG of said subjectsimultaneously to sensing said second ECG; averaging said first ECG andsaid second ECG thereby generating an average QRS waveform; determininga first Pulse Arrival Time (PAT) using the average QRS waveform and thefirst PPG aligned with the average QRS waveform; determining a secondPAT using the average QRS waveform and the second PPG aligned with theaverage QRS waveform; and determining a blood pressure of said subjectbased on a differential PAT comprising a difference between the firstPAT and the second PAT.
 2. The method of claim 1, wherein said opticalsensor comprises a camera that operates at a minimum speed of 30 framesper second.
 3. The method of claim 1, wherein said first and secondelectrodes are removable from said mobile computing device.
 4. Themethod of claim 1, wherein said mobile computing device is configured todisplay said blood pressure of said subject on said mobile computingdevice.
 5. The method of claim 1, wherein said mobile computing devicecomprises a smartphone.
 6. The method of claim 1, wherein said mobilecomputing device comprises a tablet.
 7. The method of claim 1, whereinsaid mobile computing device comprises a smartwatch.
 8. A systemcomprising: a mobile computing device comprising a processor, an opticalsensor, and a display, wherein the optical sensor is configured to sensea first PPG and a second PPG of a subject; a first electrode and asecond electrode connected to said mobile computing device, andconfigured to sense a first ECG and a second ECG of said subject; and anon-transitory computer readable storage medium encoded with a computerprogram including instructions executable by said processor to causesaid processor to: generate an average QRS waveform by averaging thefirst ECG and the second ECG; determine a first PAT using the averageQRS waveform and the first PPG aligned with the average QRS waveform;determine a second PAT using the average QRS waveform and the second PPGaligned with the average QRS waveform; and determine a blood pressure ofsaid subject based on a differential PAT comprising a difference betweenthe first PAT and the second PAT.
 9. The system of claim 8, wherein saidcomputer program including instructions executable by said processorfurther causes said processor to display said blood pressure of saidsubject on said mobile computing device.
 10. The system of claim 8,wherein the mobile computing device comprises a smartphone.
 11. Thesystem of claim 8, wherein the mobile computing device comprises atablet.
 12. The system of claim 8, wherein the mobile computing devicecomprises a smartwatch.
 13. The system of claim 8, wherein said opticalsensor is a camera that operates at a minimum speed of 30 frames persecond.
 14. The system of claim 8, wherein said optical sensor is acamera that operates at a minimum speed of 60 frames per second.
 15. Thesystem of claim 8, wherein said first and second electrodes areremovable from said mobile computing device.